FIG. 12 is a schematic top view for illustrating an interconnecting structure in a conventional semiconductor device. FIG. 13 is a sectional view taken along the line F-F′ of FIG. 12 showing the interconnecting structure manufactured using a dual damascene method.
As FIGS. 12 and 13 show, dual damascene interconnects including vias 28 connected to first wirings (M1) 15 and second wirings (M2) 29 connected to the vias 28 are formed. Furthermore, in order to eliminate density difference between wiring patterns, first dummy wirings 15a are formed on the peripheries of the first wirings 15, and second dummy wirings 29a are formed on the peripheries of the second wirings 29.
In recent years, the miniaturization of semiconductor devices has caused an accompanying problem of wiring signal delay. In order to solve such a problem, copper (Cu) is used as a wiring material, and a low-k dielectric film 30 having a low dielectric constant (k) is used as an interlayer dielectric film (for example, refer to Non-Patent Document “K. Hayashi et al., Proceedings of the 2002 International Interconnect Technology Conference, pp. 15-17”).
However, when a dimension of vias is reduced, density difference between isolated vias and dense vias is enlarged due to the proximity effect. Furthermore, when vias are formed using a low-k dielectric film as an interlayer dielectric film, and when a chemically amplified resist, such as a KrF resist and an ArF resist, is used as a mask, the problems of via resistance elevation and the occurrence of wire breaking are caused, in particular in isolated vias, by an acid of the chemically amplified resist. In other words, a problem of the occurrence of a phenomenon known as “resist poisoning” arises in vias, in particular in isolated vias. These problems are often caused when a cap film including different insulating films is formed on a low-k dielectric film in order to prevent causing ashing damage to the low-k dielectric film.
In addition, for example, in electronic devices such as high-technology logic circuit products, the source voltage is lowered to reduce power consumption. Therefore, a problem of malfunction is often caused by external noise.